Distributed 2D temperature sensing during nanoparticles assisted laser ablation by means of high-scattering fiber sensors

Abstract

The high demand in effective and minimally invasive cancer treatments, namely thermal ablation, leads to the demand for real-time multi-dimensional thermometry to evaluate the treatment effectiveness, which can be also assisted by the use of nanoparticles. We report the results of 20-nm gold and magnetic iron oxide nanoparticles-assisted laser ablation on a porcine liver phantom. The experimental setup consisting of high-scattering nanoparticle-doped fibers was operated by means of a scattering-level multiplexing arrangement and interrogated via optical backscattered reflectometry, together with a solid-state laser diode operating at 980 nm. The multiplexed 2-dimensional fiber arrangement based on nanoparticle-doped fibers allowed an accurate superficial thermal map detected in real-time. Laser ablation (LA) is a minimally invasive and alternative thermal therapy technique to the surgical resection for the treatment of cancer that aimed to destroy the tumor at high temperatures. Laser ablation works on the principle of conversion of absorbed laser light into heat in tissue leading to coagulative necrosis. The laser light inside the tumor is distributed according to the phenomena of scattering, absorption, and bending. The rate of absorption mainly depends on the water and hemoglobin load 1. The widely employed laser types for LA are Neodymium: Yttrium aluminum garnet operating at a wavelength of 1,064 nm and solid-state diode working at a wavelength of 800-980 nm due to the best light penetration ability at near-infrared region 2. However, currently, laser diodes gaining more interest and replacing the Nd: YAG laser because they are cheaper, easier to transport due to the lightweight and shows the similar tissue penetration performance at the wavelengths between 800 and 980 nm 3. In the last 4 decades, many studies have investigated the efficacy of LA for the treatment of cancer, demonstrated its advances, and evaluated the settings responsible for the therapy outcome. Indeed, the size of the heated area significantly depends on the laser power, laser wavelength, absorption features, optical properties of the biological tissue, and time of laser irradiation 4,5. In the clinical practice, laser light is delivered in different modalities depending on the location of the tumor and the desired thermal effect: deep-seated tumors in the liver 6,7 , pancreas 8,9 , brain 10 and other organs can be reached by thin optical applicators; superficial tumors like nonmelanoma skin cancer 11,12 , superficial bladder carcinoma 13 can be treated with external and non-invasive approaches. The pioneering work of laser application in tumor treatment was done by Bown in 1983 4. LA is mostly known as interstitial laser thermotherapy, where the light delivered by means of delivery fiber into the tumor, usually a large core fiber or a side-firing fiber ranging in diameter from 0.5 to 2.5 mm 14-16. The laser light is further converted into the thermal energy leading to the tumor damage. Nowadays, the reliable method of real-time

Closed-Loop Temperature Control Based on Fiber Bragg Grating Sensors for Laser Ablation of Hepatic Tissue

“…Several studies implemented fiber optic- [ 36 , 37 , 41 ] and quasi-distributed sensing [ 33 , 42 , 43 , 44 , 45 ] to monitor temperature during LA, and showed the capability of fiber optic sensors to provide spatial maps of the tissue temperature after the treatment completion. However, none of these studies investigate the performance of fiber optic sensors for temperature-based LA regulation, where also real-time monitoring is indispensable.…”

Green-Synthesized Silver Nanoparticle–Assisted Radiofrequency Ablation for Improved Thermal Treatment Distribution

“…The data was collected with an optical backscatter reflectometer (Luna OBR 4600, Luna Inc., Roanoke, VA, USA) allowing to monitor the distributed temperature change during RFA. The OBR sends a signal through a fiber link and then measures the reflection caused by Rayleigh scattering [ 54 ]. By registering the propagation time of backscattered light, return losses experienced by different points along the fiber length are determined.…”

Recent Advances in Biomedical Photonic Sensors: A Focus on Optical-Fibre-Based Sensing

“…A different strategy to FBG for 2D distributed temperature sensing was reported in [44]. Temperature monitoring was achieved by using a distributed sensor during nanoparticle (NP)-mediated ablation.…”

“…Temperature monitoring was achieved by using a distributed sensor during nanoparticle (NP)-mediated ablation. The nanoparticles (20 nm-gold and magnetic iron oxide, which provide ease of synthesis, unique properties, and biocompatibility [44]) were deposited in the tissue assisting the laser ablation of a porcine liver phantom. The setup includes a fibre-coupled laser diode (980 nm), an optical backscatter reflectometer (OBR) and four sensing high-scattering nanoparticle-doped fibres.…”